Re: UCLA TN3270 negotiation

Bob Braden (
Fri, 27 Mar 87 09:36:12 PST

        Could someone familiar with the UCLA ACP tell me at what point in
        the connection/login sequence it first negotiates 3270 mode (Term
        Type, EOR and Binary)? I have tried connecting to an UCLA MVS
        Arpanet machine, but negotiation didn't seem to take place on
        connection open (unlike WISCNET), and I didn't have an account,
        so I haven't been able to proceed further. Is my code broken,
        or do I have to log in to really test it?


Well, yes, I can tell you. Too bad you did not go to the TCP/IP
Interoperability Workshop in Monterey last week; Greg Minshall
gave a whole session on IBM 3270 support, and I described the rules for
negotiation into fullscreen mode.

Basically, VM uses a less-than-general approach to fullscreen
negotiation because of restrictions in that operating system's virtual
terminal machinery. If you simply connect to a UCLA MVS system with a
normal Telnet NVT, you will understand the problem. It does not
negotiate fullscreen mode until it is able to determine that the
particular service subsystem of the host to which you actually want to talk
handles fullscreen mode. EG, if you "logon" to TSO, it will then
try to negotiate full screen; when you logoff TSO, it will return you
to NVT mode, etc.

Since this topic is probably not of general interest, and has been
somewhat beaten to death in the past, I suggest we take any further
discussion on this off the mailing list.

Bob Braden

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